Liquid-crystalline copolymer

ABSTRACT

A liquid-crystalline copolymer having a long helical pitch, the liquid-crystalline copolymer comprises the copolymerization product of; 
     (a) at least one liquid-crystalline epoxy compound having a helical structure and 
     (b) at least one liquid-crystalline epoxy compound having a helical structure opposite in twining direction of helix to the helical structure of the liquid-crystalline epoxy compound (a) or 
     (c) at least one non-liquid-crystalline epoxy compound.

This application is a divisional of application Ser. No. 395,058, filedAug. 17, 1989 now U.S. Pat. No. 5,190,686.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a novel liquid-crystalline copolymer.More specifically, the present invention relates to a novelliquid-crystalline copolymer which exhibits ferroelectricity even attemperatures around room temperature, has a long helical pitch, and hassuch a high speed of response to external factors as to enable displayof motion pictures. Such a liquid-crystalline copolymer is useful inoptoelectronics fields as various kinds of optical elements,particularly, as those for display devices for desk calculators, clocksand watches, etc., and those for various electronic optical devices forelectronic optical shutters, electronic optical diaphragms, opticalmodulators, optical-path transfer switches in optical communicationsystems, memories, liquid crystal printer heads, varifocal lenses, etc.In particular, the liquid-crystalline copolymer of the present inventionhas a high practicality in its use as the display elements for largedisplay screens or curved display screens.

(b) Description of the Related Art

Display devices in which low molecular weight liquid crystals are usedas the display element have been widely used for digital display of deskcalculators, clocks and watches, etc. In these fields of utilization,the conventional low molecular weight liquid crystals are generallysupported between a couple of glass substrates spaced from each other inmicrons. However, such an adjustment of the space has been practicallyimpossible in production of large display screens or curved displayscreens. In order to solve the problem, some attempts have been made todevelop polymeric liquid crystals so as to render moldability to theliquid crystals themselves. For example, in Japanese Patent ApplicationKokai Koho No. 55-21479, Japanese Patent Application Kokai Koho No.63-99204, and EP-0184482 disclosed are various kinds ofpolyacrylate-type ferroelectric polymeric liquid crystals. Nevertheless,these conventional polymeric liquid crystals have hardly beensatisfactory for practical use because of their high temperature rangeswhere ferroelectricity is exhibited. Further, these polymeric liquidcrystals have deficiencies in that their speeds of response in thechanges of their transmission intensity to the changes of externalfactors such as electric field are generally slow and sufficientbistability cannot be attained because of their short helical pitches.

Since ferroelectric liquid crystals exhibiting chiral smectic C phase(SmC* phase) have a layered structure and the director `n` of themolecules gradually rotates about the normal line of the layers witheach layer, the directors `n` of the molecules on the whole construct ahelical structure. The distance between the planes perpendicular to thehelical axis required by the director to rotate for 360° is calledhelical pitch. For instance, DOBAMBC has a helical pitch of from 2 to 3μm which, considering the size of the molecule, indicates that one pitchconsists of molecule layers close to 1000. In comparison with theconventional nematic liquid crystals, ferroelectric liquid crystals arecharacteristically used as the materials of display devices because oftheir high speed response property and bistability (memory property).There exists a close connection between bistability and the helicalpitch of ferroelectric liquid crystals, and, in order to obtain adisplay device having bistability, it is necessary to make the cell gap`d` smaller than the helical pitch `p` so that the ferroelectric liquidcrystal operates at a state with its helix loosened. For this reason,there has been a demand for development of ferroelectric liquid crystalmaterials having long helical pitches.

SUMMARY OF THE INVENTION

Accordingly, the object of the present invention is to provide a liquidcrystal polymer which not only exhibits ferroelectricity even attemperatures neighboring room temperature but also has high speed ofresponse to external factors enabling display of motion pictures and, aswell, can be advantageously used as the display element for displaydevices having a large display screen or curved screen.

As the result of repeated researches for solving the above problems, wefound that a liquid-crystalline copolymer obtainable by copolymerizingtwo liquid-crystalline epoxy monomers having specified structures andbeing opposite in twining direction of helix to each other or bycopolymerizing a liquid-crystalline epoxy monomer and anon-liquid-crystalline epoxy monomer exhibits a high speed responsewithin a wide temperature range neighboring room temperature and has along helical pitch, and we eventually completed the present invention.

Thus, the present invention provides a liquid-crystalline copolymercomprising the copolymerization product of;

(a) at least one liquid-crystalline epoxy compound having a helicalstructure and

(b) at least one liquid-crystalline epoxy compound having a helicalstructure opposite in twining direction of helix to the helicalstructure of the liquid-crystalline epoxy compound (a) or

(c) at least one non-liquid-crystalline epoxy compound.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a chart showing an NMR spectrum of the liquid-crystallinecopolymer prepared in Example 1.

FIG. 2 is a chart showing an NMR spectrum of the liquid-crystallinecopolymer prepared in Example 2.

FIG. 3 is a chart showing an NMR spectrum of the liquid-crystallinecopolymer prepared in Example 3.

FIG. 4 is a chart showing an NMR spectrum of the liquid-crystallinecopolymer prepared in Example 4.

FIG. 5 is a chart showing an NMR spectrum of the liquid-crystallinecopolymer prepared in Example 7.

FIG. 6 is a chart showing an NMR spectrum of the liquid-crystallinecopolymer prepared in Example 8.

FIG. 7 is a chart showing an NMR spectrum of the liquid-crystallinecopolymer prepared in Example 9.

FIG. 8 is a chart showing an NMR spectrum of the liquid-crystallinecopolymer prepared in Example 10.

FIG. 9 is a chart showing an NMR spectrum of the liquid-crystallinecopolymer prepared in Example 11.

FIG. 10 is a chart showing an NMR spectrum of the liquid-crystallinecopolymer prepared in Example 12.

FIG. 11 is a chart showing an NMR spectrum of the liquid-crystallinecopolymer prepared in Example 13.

FIG. 12 is a chart showing an NMR spectrum of the liquid-crystallinecopolymer prepared in Example 14.

FIG. 13 is a chart showing an NMR spectrum of the liquid-crystallinecopolymer prepared in Example 15.

FIG. 14 is a chart showing an NMR spectrum of the liquid-crystallinecopolymer prepared in Example 16.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

One of the preferred embodiments of the liquid-crystalline copolymers ofthe present invention is a liquid-crystalline copolymer comprising thecopolymerization product of;

(a) at least one liquid-crystalline epoxy compound which has a helicalstructure and is represented by the following general formula (1) and

(b) at least one liquid-crystalline epoxy compound which has a helicalstructure opposite in twining direction of helix to the helicalstructure of the liquid-crystalline epoxy compound (a) and isrepresented by the following general formula (2),

the copolymerization product comprising at least one repeating unitrepresented by the following general formula (3) and at least onerepeating unit represented by the following general formula (4), whereinthe molar ratio of the repeating unit (3) to the repeating unit (4) isfrom 99:1 to 1:99; ##STR1## wherein R¹ and R² are different from eachother and each independently are a group represented by --(CH₂)_(k)--OR³,

wherein

k is an integer having a value of from 1 to 30,

R³ is a group represented by --A_(p) --X--B_(q) --R⁴, wherein

X is a single bond, --COO-- or --OCO--,

p and q each independently are an integer having a value of 1 or 2,

A is ##STR2## a and b each independently being an integer having a valueof from 0 to 4 and being identical with or different from each other,each Y being a halogen atom and being identical with or different fromthe others,

A and B are identical with or different from each other, and

R⁴ is --COOR⁵, --OCOR⁵ or --OR⁵,

wherein

R⁵ is ##STR3## R⁶ and R⁷ each independently being --CH₃, a halogen atom,--CN or --CF₃, r and t each independently being an integer having avalue of from 0 to 10, with the proviso that t is not 0 when R⁷ is--CH₃, s being an integer of 0 or 1, and C marked with * being anasymmetric carbon atom.

Liquid-crystalline molecules exhibiting a chiral smectic phase or chiralnematic phase construct a helical structure, and the twining directionof the helical structure (clockwise twining: R, anticlockwise twining:L) depends on the structure of the optically active group, the type ofthe stereoisomerism of the asymmetric carbon atoms in the opticallyactive group (i.e., R configuration or S configuration), the distance offrom the skeletal portion to the asymmetric carbon atom in the opticallyactive group, and so on. Copolymerization of two monomers whosestructure molecules are opposite in twining direction of helix to eachother provides a liquid-crystalline copolymer in which two kinds ofcopolymer units opposite in twining direction of helix to each otherexist together. In this liquid-crystalline copolymer, the helicalproperties of the two kinds of copolymer units compensate each other,resulting in an extended helical pitch of the copolymer. The extendedhelical pitch makes it unnecessary to adjust the thickness of liquidcrystal cells accurately to about 1 to 2 μm, thereby offering anadvantage in preparation of devises.

In the above formula, k is an integer having a value of from 1 to 30,and the preferred value is from 4 to 16. The preferred value of r is 0to 2.

In the above formula, some illustrative examples of A and B include thegroups represented by the following formulas, respectively: ##STR4##

Typical examples of R³ include ##STR5##

In the above formulas, some illustrative examples of the opticallyactive group R⁵ include 2-methylbutyl group, 2-fluorooctyl group,2-chloro-1-methylpropyl group, 2-cyanobutyl group,1-(trifluoromethyl)heptyl group, 1-methylpropyl group, 1-methylbutylgroup, 3-methylpentyl group, and 3-chloro-2-methylpentyl group.

Among various applicable combinations of R¹ and R², some examples of thepreferred combinations include a combination of R¹ wherein R⁴ is##STR6## t being preferably an integer having a value of 2 to 5 and acombination of R¹ wherein R⁴ is ##STR7## t being preferably an integerhaving a value of from 3 to 5.

Further, in order to facilitate controlling the temperature ranges ofliquid crystal phases, it is preferable to use one liquid-crystallineepoxy compound having a two-cyclic structure and the otherliquid-crystalline epoxy compound having a three-cyclic structure, incombination.

As the liquid-crystalline epoxy compounds represented by the formulas(1) and (2) to be used for preparation of the copolymerization productin the present invention, a combination of those opposite in twiningdirection of helix to each other is used.

Typical examples of the liquid-crystalline epoxy compound having Rconfiguration (clockwise twining) include ##STR8## and typical examplesof the liquid-crystalline epoxy compound having L configuration(anticlockwise twining) include ##STR9##

At least one epoxy compound of R configuration and at least one epoxycompound of L configuration, for example, those shown above, arecombined properly to be copolymerized so that the molar ratio of therepeating unit (3) to the repeating unit (4) becomes from 99:1 to 1:99,preferably from 80:20 to 20:80. If the molar ratio deviates from therange of from 99:1 to 1:99, the effect of extending the helical pitchcannot be expected.

The preferred number average molecular weight of the liquid-crystallinecopolymer is from 1,000 to 500,000. If the number average molecularweight is less than 1,000, the moldability of the copolymer into film orcoated film will be occasionally deteriorated. If it is more than500,000, there will occasionally appear undesirable effects such aslowered response speed. Although the particularly preferred range of thenumber average molecular weight cannot be defined uniformly since itdepends on the kinds of R¹ and R², the numerical value of k, the opticalpurity of R⁵, etc., it is generally from 1,000 to 200,000.

Another preferred embodiment of the liquid-crystalline copolymers of thepresent invention is a liquid-crystalline copolymer comprising thecopolymerization product of;

(a) at least one liquid-crystalline epoxy compound which has a helicalstructure and is represented by the following general formula (1) and

(c) at least one non-liquid-crystalline epoxy compound represented bythe following general formula (5),

the copolymerization product comprising at least one repeating unitrepresented by the following general formula (3) and at least onerepeating unit represented by the following general formula (6), whereinthe molar ratio of the repeating unit (3) to the repeating unit (6) isfrom 99:1 to 10:90; ##STR10## wherein

R¹ is a group represented by --(CH₂)_(k) --OR³,

wherein

k is an integer having a value of from 1 to 30,

R³ is a group represented by --A_(p) --X--B_(q) --R⁴, wherein

X is a single bond, --COO-- or --OCO--,

p and q each independently are an integer having a value of 1 or 2,

A is ##STR11##

a and b each independently being an integer having a value of from 0 to4 and being identical with or different from each other, each Y being ahalogen atom and being identical with or different from the others,

A and B are identical with or different from each other, and

R⁴ is --COOR⁵, --OCOR⁵ or --OR⁵,

wherein

R⁵ is ##STR12##

R⁶ and R⁷ each independently being --CH₃, a halogen atom, --CN or --CF₃,r and t each independently being an integer having a value of from 0 to10, with the proviso that t is not 0 when R⁷ is --CH₃, s being aninteger of 0 or 1, and C marked with * being an asymmetric carbon atom;and

R⁸ is --H or a group represented by --(CH₂)_(u) CH₃, u being an integerhaving a value of from 0 to 9.

That is, copolymerization of a liquid-crystalline monomer having ahelical structure with an epoxy monomer without helical structureprovides a liquid-crystalline copolymer in which a copolymer unit havinga helical structure and a copolymer unit without helical structurecoexist. In this copolymer, the helical properties of the copolymer unithaving a helical structure is weakened by the dilution effect of thecopolymer unit without helical structure, resulting in an extendedhelical pitch of the resulting copolymer. At the same time, the presenceof the non-liquid-crystalline copolymer unit enables the ferroelectricphase temperature range of a liquid-crystalline polymer exhibiting, initself, ferroelectric phase at a higher temperature range to be loweredto a temperature neighboring room temperature.

The liquid-crystalline copolymer can be prepared by copolymerizing acombination of at least one monomer represented by the general formula(1) and at least one monomer represented by the general formula (5) sothat the molar ratio of the repeating unit represented by the generalformula (3) to the repeating unit represented by the general formula (6)becomes from 99:1 to 10:90, preferably from 90:10 to 20:80. If the molarratio deviates from the range of from 99:1 to 10:90, there cannot beexpected extension of the helical pitch nor sufficiently high speedresponse.

The preferred number average molecular weight of the liquid-crystallinecopolymer described above is from 1,000 to 500,000. If the numberaverage molecular weight is less than 1,000, the moldability of thecopolymer into film or coated film will be occasionally deteriorated. Ifit is more than 500,000, there will occasionally appear undesirableeffects such as lowered response speed. Although the particularlypreferred range of the number average molecular weight cannot be defineduniformly since it depends on the kinds of R¹ and R⁸, the numericalvalues of k and u, the optical purity of R⁵, etc., it is generally from1,000 to 200,000.

Hereinafter, there will be described general methods of synthesizing theliquid-crystalline epoxy compounds to be used as the monomers (1) and(2) for the liquid-crystalline copolymer of the present invention.##STR13##

As shown by the following reaction formulas, at first, an alkenol (I) ishalogenized with a halogenizing agent, such as thionyl chloride, in thepresence of pyridine, to obtain an alkene halide (II). The alkene halide(II) is reacted with a compound (III) in a proper solvent, such as2-butanone, in the presence of an alkali, such as potassium carbonate,to obtain an ether compound (IV). Subsequently, the ether compound (IV)is epoxidized with a per acid, such as m-chloroperbenzoic acid, in aproper solvent, such as dichloromethane, to obtain the objective monomer(V). ##STR14##

The preferred examples of the alkenol (I) include 9-decene-1-ol,11-dodecene-1-ol, 7-octene-1-ol, and 13-tetradecene-1-ol.

The above described compound (III), ##STR15## can be synthesized asfollows.

Synthesis of ##STR16##

As shown by the following reaction formula, the objective ester compound(VII) is prepared by reacting 4'-hydroxybiphenyl-4-carboxylic acid withan optically active alcohol (VI) in a proper solvent, such as benzene,at a desired temperature, in the presence of an esterification catalyst,such as concentrated sulfuric acid or p-toluenesulfonic acid. ##STR17##

Some illustrative examples of the optically active alcohol (VI) whichmay be used include

(R)-2-methylbutanol, (S)-2-methylbutanol,

(R)-4-methylhexanol, (S)-4-methylhexanol,

(R)-2-chloropropanol, (S)-2-chloropropanol,

(R)-2-cyanopropanol, (S)-2-cyanopropanol,

(R)-4-chloropentanol, (S)-4-chloropentanol,

(R)-2-butanol, (S)-2-butanol, (S)-2-pentanol,

(R)-2-pentanol, (S)-2-octanol, (R)-2-octanol,

(S)-2-fluorooctanol, (R)-2-fluorooctanol,

(S)-2-fluorononanol, (R)-2-fluorononanol,

(2S, 3S)-2-chloro-3-methyl-1-pentanol,

(2S, 3S)-2-fluoro-3-methyl-1-pentanol,

(2S, 3S)-2-bromo-3-methyl-1-pentanol,

(3S, 4S)-3-chloro-4-methyl-1-hexanol,

(4S, 5S)-4-chloro-5-methyl-1-heptanol,

(5S, 6S)-5-chloro-6-methyl-1-octanol,

(6S, 7S)-6-chloro-7-methyl-1-nonanol,

(R)-(+)-1,1,1-trifluoro-2-octanol, 3-chloro-2-butanol, and

(S)-(+)-3-methylpentanol.

Synthesis of ##STR18##

As shown by the following reaction formula, the objective ester compound(IX) may be prepared by reacting biphenyl-4,4'-diol with an opticallyactive carboxylic acid (VIII). ##STR19##

Some illustrative examples of the optically active carboxylic acid(VIII) which may be used include

(R)-2-methylbutanoic acid, (S)-2-methylbutanoic acid,

(2S, 3S)-2-chloro-3-methylpentanoic acid,

(2S, 3S)-2-fluoro-3-methylpentanoic acid,

(R)-2-methylpentanoic acid, (S)-2-methylpentanoic acid,

(R)-3-methylpentanoic acid, (S)-3-methylpentanoic acid,

(R)-4-methylhexanoic acid, (S)-4-methylhexanoic acid,

(R)-2-chloropropanoic acid, (S)-2-chloropropanoic acid,

(R)-6-methyloctanoic acid, (S)-6-methyloctanoic acid,

(R)-2-cyanobutanoic acid, (S)-2-cyanobutanoic acid,

(R)-2-cyanopropanoic acid, and (S)-2-cyanopropanoic acid.

Synthesis of ##STR20##

As shown by the following reaction formulas, the above-describedoptically active alcohol (VI) is tosylated and then reacted withbiphenyl-4,4'-diol, to obtain the objective ether compound (X).##STR21##

As shown by the following reaction formulas, at first, an alkene halide(II) is reacted with ethyl p-hydroxybenzoate in a proper solvent, suchas acetone, in the presence of an alkali, such as potassium carbonate,to obtain an ether compound. Subsequently, the group protecting thecarboxyl group in the ether compound is eliminated by using an aqueouspotassium hydroxide solution, hydrochloric acid, etc., to obtain ancarboxylic acid compound. The carboxylic acid is converted into an acidhalide by adding a halogenating agent, such as thionyl chloride, andheating the obtained mixture in a solvent, such as toluene. The acidhalide is reacted with the above-described compound (III) in a solvent,such as toluene, in the presence of pyridine, to obtain an estercompound (XI), and the obtained ester compound (XI) is epoxidized in aproper solvent, such as dichloromethane, by using a per acid, such asm-chloroperbenzoic acid, to obtain the objective monomer (XII).##STR22##

As shown by the following reaction formulas, at first, an alkene halide(II) is reacted with hydroquinone in the presence of an alkali, such aspotassium carbonate, to obtain an ether compound (XIII).

The compound (XIV) described below is converted into an acid chloridewith thionyl chloride or the like. The obtained acid chloride is reactedwith the ether compound (XIII) in the presence of pyridine, to obtain anester compound (XV). After this, epoxidation is carried out in the samemanner as in the case (1), to obtain the objective monomer (XVI).##STR23##

The above-described compound (XIV), ##STR24## may be prepared asfollows.

Synthesis of ##STR25##

An optically active alcohol (VI) is reacted withbiphenyl-4,4'-dicarboxylic acid in a solvent, such as toluene, in thepresence of an esterification catalyst, to obtain the objective estercompound (XVII). ##STR26##

Synthesis of ##STR27##

After an optically active carboxylic acid (VIII) is converted into anacid chloride by using thionyl chloride or the like, the obtained acidchloride is reacted with 4'-hydroxybiphenyl-4-carboxylic acid in thepresence of pyridine, to obtain the objective ester compound (XVIII).##STR28##

Synthesis of ##STR29##

Ethyl 4'-hydroxybiphenyl-4-carboxylate and ##STR30## which is preparedby tosylating an optically active alcohol (VI), are reacted in thepresence of potassium carbonate or the like, to obtain an ethercompound. The obtained ether compound is reacted with an aqueous alkalisolution to hydrolyze the ester portion to eliminate the protectinggroup, and the objective compound (XIX) is obtained. ##STR31##

The objective monomer (XXI) may be prepared in the same manner as in thesynthetic method (2) for preparing the monomer wherein R³ is ##STR32##with the exception that the compound (III), ##STR33## is replaced by acompound (XX), ##STR34##

The above-described compound (XX) may be prepared as follows.

Synthesis of ##STR35##

The objective ester compound (XXII) may be prepared in the same manneras in the synthetic method for preparing the compound (VII) in the case(1), with the exception that 4'-hydroxybiphenyl-4-carboxylic acid isreplaced by p-hydroxybenzoic acid.

Synthesis of ##STR36##

The objective ester compound (XXIII) may be prepared in the same manneras in the synthetic method for preparing the compound (VIII) in the case(1), with the exception that biphenyl-4,4'-diol is replaced byhydroquinone.

Synthesis of ##STR37##

The objective ether compound (XXIV) may be prepared in the same manneras in the synthetic method for preparing the compound (X) in the case(1), with the exception that biphenyl-4,4'-diol is replaced byhydroquinone. ##STR38##

As shown by the following reaction formulas, the objective monomer(XXVI) may be prepared in the same manner as in the synthetic method (3)for preparing the monomer wherein R³ is ##STR39## with the exceptionthat the compound (XIV), ##STR40## is replaced by a compound (XXV),##STR41##

The above-described compound (XXV) may be prepared as follows.

Synthesis of ##STR42##

The objective ester compound (XXVII) may be prepared in the same manneras in the synthetic method for preparing the compound (XVII) in the case(3), with the exception that biphenyl-4,4'-dicarboxylic acid is replacedby terephthalic acid. ##STR43##

Synthesis of ##STR44##

The objective ester compound (XXVIII) may be prepared in the same manneras in the synthetic method for preparing the compound (XVIII) in thecase (3), with the exception that 4'-hydroxybiphenyl-4-carboxylic acidis replaced by p-hydroxybenzoic acid. ##STR45##

Synthesis of ##STR46##

The objective ether compound (XXIX) may be prepared in the same manneras in the synthetic method for preparing the compound (XIV) in the case(3), with the exception that ethyl 4'-hydroxybiphenyl-4-carboxylate isreplaced by ethyl p-hydroxybenzoate. ##STR47##

The objective monomer (XXX) may be prepared in the same manner as in thesynthetic method (2) for preparing the monomer wherein R³ is ##STR48##with the exception that ethyl p-hydroxybenzoate is replaced by ethyl4'-hydroxybiphenyl-4-carboxylate, and the compound (III), ##STR49## isreplaced by a compound (XX), ##STR50##

The objective monomer (XXXI) may be prepared in the same manner as inthe synthetic method (3) for preparing the compound wherein R³ is##STR51## with the exception that hydroquinone is replaced bybiphenyl-4,4'-diol, and the compound (XIV), ##STR52## is replaced by theabove-described compound (XXV), ##STR53##

Other epoxy compounds containing aromatic rings A and/or B substitutedwith halogen atoms also may be synthesized according to theabove-described methods.

Typical examples of the non-liquid-crystalline epoxy compound (c)represented by the general formula (5) having no helical structure,which is to be used as the other kind of copolymerizing monomer in thepresent invention, include ethylene oxide, propylene oxide, and1,2-epoxyhexane.

The liquid-crystalline copolymer of the present invention is prepared bycopolymerizing thus obtained two or more monomers having helicalstructures which are combined to include at least two epoxy compoundsopposite in twining direction of helix to each other, or bycopolymerizing thus obtained at least one liquid-crystalline monomerhaving a helical structure with at least one non-liquid-crystallineepoxy comonomer, and the copolymerization can be performed by usingknown cationic polymerization methods, or the like.

The catalysts that may be employed for the cationic copolymerization inthe present invention are known ones including protonic acids, such assulfuric acid, phosphoric acid or perchloric acid, lewis acids, such asboron trifluoride, aluminum chloride, titanium tetrachloride or stannicchloride, boron trifluoride etherate, etc. Among these catalysts,stannic chloride may be suitably used.

It is also possible to prepare the copolymers of the present inventionby coordination polymerization by using organic aluminum complexes, etc.as a catalyst. In this case, copolymers having number average molecularweights of not less than 30,000 can be obtained.

The polymerization techniques that may be employed in the presentinvention are bulk polymerization technique, slurry polymerizationtechnique, solution polymerization technique, etc., preferably solutionpolymerization technique.

The suitable polymerization temperature can be usually from 0° to 30°C., although it is not uniformly specified since it varies depending onthe kind of the catalyst.

The suitable polymerization time can be usually from several hours tosix days, although it varies depending on the other polymerizationconditions including the polymerization temperature, etc.

The control of the molecular weights of the copolymers may be conductedby addition of a known molecular weight regulator and/or control of theconcentration of catalyst to monomers.

When bulk polymerization technique is employed, the resulting copolymersmay be directly fixed between a couple of substrates in a state adheringto the substrates by sufficiently mixing the monomers with an initiator,sufficiently de-aerating the mixture, introducing the mixture betweentwo substrates such as glass substrates, and heating.

The solvents to be used in slurry polymerization and solutionpolymerization may be any known inert solvent. The illustrative examplesof the solvents to be suitably used include hexane, dichloromethane oraromatic solvents, such as benzene, toluene, and xylene.

It is not essential but preferable to replace the atmosphere of thereaction system with an inert gas, such as argon or nitrogen, at thetime of copolymerization reaction and the above-described epoxidationreaction.

Thus obtained copolymers of the present invention may be used by formingthem into films by using a known film forming technique, such as castingtechnique, T-die technique, inflation technique, calender technique,stretching technique or the like. Thus obtained films of the copolymersof the present invention may be used in various optoelectronics fields,such as liquid crystal displays, electronic optical shutters, electronicoptical diaphragms, and the like, by disposing them between a couple oflarge glass substrates, curved glass substrates, polyester films, etc.,not to mention two usual glass substrates. Further, the polymers mayalso be directly formed into films adhering to a substrate by dissolvinga copolymer in a suitable solvent, applying the resulting copolymersolution to a surface of a substrate, such as glass substrate, and thenevaporating the solvent.

From the results of measurements of the helical pitch and phasetransition temperature, it was confirmed that the copolymers of thepresent invention have extended helical pitches longer than thecorresponding homopolymers and take chiral smectic C phase liquidcrystal state over a wide temperature range including temperaturesaround room temperature. It was also confirmed that they perform highspeed response at temperatures around room temperature.

The copolymers of the present invention have both the properties ofsmectic phase liquid crystal and the typical property of polymers, i.e.,an excellent moldability, and they have a large possibility of usage inthe fields of integrated optics, optoelectronics, and informationmemory. For instance, the copolymers of the present invention may beused as various electronic optical elements, for example, for liquidcrystal displays, such as digital displays of various forms, electronicoptical shutters, optical-path transfer switches in opticalcommunication systems, electronic optical diaphragms, memory devices,optical modulators, liquid crystal optical printer heads, and varifocallenses.

The copolymers of the present invention may be further improved byvarious treatments well known in this industry, for example, by mixingtwo or more copolymers of the present invention, mixing them with otherpolymers, addition of additives such as various inorganic or organiccompounds or metals, including stabilizers, plasticizers, etc.

In order to fully and clearly illustrate the present invention, thefollowing examples are presented. It is intended that the examples beconsidered illustrative rather than limiting the invention disclosed andclaimed herein.

EXAMPLES 1 TO 18 AND COMPARATIVE EXAMPLES 1 TO 5

The structures of the polymers obtained in the Examples and ComparativeExamples were identified by NMR, IR, and elementary analysis. Themeasurement of phase transistion temperatures and identification of thephases were each conducted by the use of a DSC and a polarizingmicroscope, respectively.

The NMR charts of the copolymers obtained in Examples 1 to 4 are shownin FIGS. 1 to 4, respectively, and the NMR charts of the copolymersobtained in Examples 7 to 18 are shown in FIGS. 5 to 16, respectively.

The molar ratios of copolymer units, phase transition behaviors, helicalpitches, and response speeds to electric field of the copolymersobtained in Examples 1 to 6 and the copolymers obtained in Examples 7 to18 are shown in Tables 1 and 2, respectively. (g: glass state, Sm1: anunidentified smectic phase, SmC*: chiral smectic C phase, SmA: smectic Aphase, N: nematic phase, N*: chiral nematic phase, Iso: isotropicphase.) The numerals in the phase transition behavior schemes representthe phase transition temperatures in °C. unit.

The measurements of the twining direction, helical pitch, and responsespeed to electric field were conducted as follows.

Measurement of the twining direction

The twining direction of each liquid-crystalline epoxy compound having ahelical structure was defined by placing, on a glass plate, theliquid-crystalline epoxy compound and a ferroelectric liquid crystalhaving a known twining direction next to each other, further placing acover glass thereon, and then visually observing with a polarizingmicroscope whether the helical pitch in the mixed portion would becomelonger than those of the above two compounds (Contact method). Alengthened helical pitch indicates that these two compounds are oppositein twining direction of helix to each other.

Measurement of the helical pitch

A liquid crystal sample was supported between two untreated ITOsubstrates and was adjusted to 100 μm in thickness. Subsequently, theobtained specimen was heated up to the transition temperature toisotropic phase and was then cooled with a cooling speed of 1° C./min.During the drop in temperature, an optically microscopic photograph ofthe striped pattern appeared in SmC* phase was taken to calculate thehelical pitch from the observed space between the stripes.

Measurement of the response speed to electric field

A polymer was supported between two ITO substrates of 20×10 mm and wasadjusted to 25 μm in thickness by spacers. An alternative current ofE=2×10⁶ V/m was applied on the obtained specimen, and the response timerequired of the light transmittance to change from 0% to 90% wasmeasured.

EXAMPLE 1 ##STR54## 1. (1) Synthesis of 4-(2-methylbutoxy)phenol

Into a n-butanol suspension containing 37 mmol (9.0 g) of 2-methylbutylp-toluenesulfonate prepared by tosylating S-(-)-2-methylbutanol and 74mmol (8.2 g) of hydroquinone, added dropwise was a solution of 50 mmol(2.1 g) of sodium hydroxide dissolved in a solvent mixture comprising 3ml of water and 10 ml of n-butanol, and the obtained mixture was thenstirred for 8 hours at 120° C. After addition of water, the reactionsolution was extracted with ether, and the extracted solution was driedand concentrated. The resulting concentrate was purified by columnchromatography to obtain 4.8 g of the objective ether compound (Yield:72%).

1.(2) Synthesis of 4-(2-methylbutoxy)phenyl 4-(9-decenyloxy)benzoate

10.0 g of 10-chloro-1-decene was allowed to react with 25 g of sodiumiodide for 10 hours at 80° C. in 2-butanone to replace the chloro groupwith an iodo group. After the reaction solution was washed with waterand dried, the solvent was removed out. To the resulting residue addedwere 11.5 g of ethyl p-hydroxybenzoate and 9.6 g of potassium carbonate,and the resulting mixture was then refluxed for 15 hours in absoluteethanol. Subsequently, to the reaction solution added was an aqueoussolution of potassium hydroxide containing 4.0 g of potassium hydroxide,and the obtained mixture was heated for 5 hours at 80° C. Afterconclusion of the reaction, the reaction solution was acidified withhydrochloric acid and then concentrated under reduced pressure. Waterwas added to the residue to form a suspension, and the insoluble matterin the suspension was collected and dried, to obtain 9.5 of4-(9-decenyloxy)benzoic acid. (Yield: 60%).

Subsequently, a toluene solution containing 10 mmol (2.8 g) of4-(9-decenyloxy)benzoic acid and 30 mmol (3.6 g) of thionyl chloride wasallowed to react for 3 hours at 100° C., and the resulting reactionsolution was concentrated under reduced pressure to obtain an acidchloride compound. A solution of the acid chloride compound dissolved in5 ml of THF was added dropwise in a solution of 8 mmol (1.4 g) of theether compound obtained in 1.(1) and 2 ml of triethylamine dissolved in20 ml of THF, and the obtained mixture was stirred for 10 hours. Afteraddition of water, the reaction solution was extracted with ether, andthe extracted solution was dried and concentrated. The concentrate wasthen purified by column chromatography to obtain 2.2 g of the objectivealkene compound. (Yield: 63%).

1.(3) Epoxidation

After a stream of gaseous argon was passed through a solution of 2 mmol(0.84 g) of the alkene compound obtained in 1.(2) and 3 mmol (0.52 g) ofm-chloroperbenzoic acid dissolved in 10 ml of methylene chloride todisplace the air in the solution and the reaction apparatus, thesolution was stirred for 10 hours. The resulting reaction solution waswashed with an aqueous potassium carbonate solution, dried, andconcentrated, to obtain 0.82 g of a monomer (L configuration)represented by the following formula. (Yield: 90%) ##STR55##

1.(4) Synthesis of 2-methylbutyl p-hydroxybenzoate

4.0 g of p-hydroxybenzoic acid and 12.5 g of (S)-(-)-2-methylbutanolwere refluxed for 6 hours in toluene in the presence of sulfuric acid,while the generated water was removed out. Subsequently, the reactionsolution was washed with water to remove sulfuric acid out. After theresulting solution was dried and concentrated, the concentrate waspurified by column chromatography to obtain 5.0 g of the objective estercompound (liquid state at room temperature, [α]_(D) ²³ =+4.9° (CHCl₃)).(Yield: 83%)

1.(5) Synthesis of 2-methylbutyl 4-[4'-(9-decenyloxy)benzoyloxy]benzoate

To 4.5 g of 4-(9-decenyloxy)benzoic acid prepared in the same manner asin 1. (2) added was toluene, and the mixture was cooled in an ice bath.During cooling of the mixture in the ice bath, 3.5 g of thionyl chloridewas further added dropwise to the mixture. After conclusion of dropping,reaction was carried out for 7 hours at 80° C. After conclusion of thereaction, the reaction solution was concentrated to obtain an acidchloride compound. While, 4.5 g of 2-methylbutyl 4-hydroxybenzoateobtained in 1. (4) and 1.8 g of pyridine were dissolved in toluene andthe obtained solution was cooled in an ice bath. Thereto added dropwisewas a toluene solution of the above-described acid chloride compound.After conclusion of dropping, reaction was carried out for 5 hours at50° C. After conclusion of the reaction, the product was washed withwater and dried over magnesium sulfate, to obtain 5.5 g of the objectivealkene compound. (Yield: 72%)

1.(6) Epoxidation

5.5 g of the alkene compound obtained in 1. (5) was subjected to thesame procedure as in 1. (3), to obtain 5.2 g of a monomer (Rconfiguration) represented by the following formula. (Yield: 92%)##STR56##

1.(7) Synthesis of polymer

After a stream of gaseous argon was passed through a solution of 1.0mmol (0.48 g) of the monomer synthesized in 1.(6) and 1.0 mmol (0.45 g)of the monomer synthesized in 1.(3) dissolved in 10 ml of methylenechloride to displace the air in the solution and the reaction apparatus,0.20 mmol of stannic chloride was added to the solution, and the mixturewas allowed to stand for 5 days at room temperature. After the resultingreaction solution was concentrated, the concentrate was purified bycolumn chromatography to obtain 0.70 g of a polymer (conversion rate:75%, Mn=3,200, copolymerization ratio m:n according to NMRspectrum=58:42).

EXAMPLE 2 ##STR57## 2.(1) Synthesis of 2-fluorooctyl p-hydroxybenzoicacid

11 g of thionyl chloride was added dropwise to 5.4 g of p-acetoxybenzoicacid. The mixture was then heated to 80° C. and wan allowed to react for3 hours. After conclusion of the reaction, the excessive thionylchloride was distilled out from the reaction solution under reducedpressure to obtain an acid chloride compound. The acid chloride compoundwas dissolved in toluene and the obtained solution was then cooled in anice bath. Thereto added was a toluene solution containing 4.4 g of(-)-2-fluorooctanol and 3 g of pyridine. the resulting mixture wasstirred overnight at room temperature. After conclusion of the reaction,the reaction solution was washed with water, dried, and concentratedunder reduced pressure. The resulting residue was dissolved in ether, 10g of benzyl amine was added dropwise to the solution. The mixture wasstirred for 5 hours at room temperature. After conclusion of thereaction, the product was washed with water, dried and concentratedunder reduced pressure. The resulting residue was purified by columnchromatography to obtain 4.9 g of the objective ester compound. (Yield:73%)

2.(2) Synthesis of 2-fluorooctyl 4-[4'-(9-decenyloxy)benzoyloxy]benzoate

To 3.0 g of 4-(9-decenyloxy)benzoic acid prepared in the same manner asin 1.(2) in Example 1 added was toluene, and the mixture was cooled inan ice bath. 2.0 g of thionyl chloride was added to the toluene solutiondropwise. Subsequently, reaction was carried out at 80° C. for 3 hours.After conclusion of the reaction, the product was concentrated to obtainan acid chloride compound. while, 1.7 g of 2-fluorooctyl4-hydroxybenzoate obtained in 2.(1) and 0.9 g of pyridine were dissolvedin toluene, and the resulting solution was cooled in an ice bath.Thereto added dropwise was a toluene solution of the abovedescribed acidchloride compound. Subsequently, reaction was carried out at roomtemperature for 15 hours. After conclusion of the reaction, the productwas washed with water and dried over magnesium sulfate, and the thesolvent was removed out from the dried product under reduced pressure.The residue was purified by column chromatography to obtain 2.8 g of theobjective ester compound. (Yield: 85%)

2.(3) Epoxidation

2.8 g of the ester compound obtained in 2.(2) was subjected to the sameprocedure as in 1.(3) in Example 1, to obtain 2.6 g of a monomer (Lconfiguration) represented by the following formula. (Yield: 91%)##STR58##

2.(4) Synthesis of polymer

After a stream of gaseous argon was passed through a solution of 1.0mmol (0.48 g) of the monomer synthesized in 1.(6) in Example 1 and 1.0mmol (0.54 g) of the monomer synthesized in 2.(3) dissolved in 10 ml ofmethylene chloride to displace the air in the solution and the reactionapparatus, 0.20 mmol of stannic chloride was added to the solution, andthe mixture was then allowed to stand for 5 days at room temperature.After concentration of the reaction solution, the concentrate waspurified by column chromatography to obtain 0.72 g of a polymer(conversion rate: 71%, Mn=2,500, copolymerization ratio m:n according toNMR spectrum=60:40).

EXAMPLE 3 ##STR59## 3.(1) Synthesis of 2-chloro-1-methylpentyl4-hydroxybenzoate

A solution of 30 mmol (5.4 g) of 4-acetoxybenzoic acid and 90 mmol (10.8g) of thionyl chloride dissolved in 100 ml of toluene was stirred for 2hours at 80° C., and the reaction solution was concentrated underreduced pressure, to obtain an acid chloride compound. Into a solutionof 10 mmol (1.1 g) of (-)-3-chloro-2-butanol and 5 ml of triethylaminedissolved in 30 ml of THF added dropwise was a solution of the aboveacid chloride compound dissolved in 10 ml of THF, and the mixture wasthen stirred for 10 hours. After concentration of the reaction solution,water was added to the concentrate, and the resulting mixture was thenextracted with ether. After concentration of the extracted solution, theconcentrate was dissolved in 200 ml of ether, and the resulting solutionwas stirred for 5 hours after addition of 20 ml of benzylamine. Thereaction solution was washed with water and then purified by columnchromatography to obtain 1.6 g of the objective hydroxy compound.(Yield: 70%)

3.(2) Synthesis of 2-chloro-1-methylpentyl4-[4'-{4"-9-decenyloxy)phenyl}benzoyloxy]benzoate

A solution of 7 mmol (2.5 g) of 4-[4'-(9-decenyloxy)phenyl]benzoic acidand 21 mmol (2.5 g) of thionyl chloride dissolved in 30 ml of toluenewas stirred for 2 hours at 80° C., and the resulting reaction solutionwas concentrated under reduced pressure to obtain an acid chloridecompound. A solution of the acid chloride compound dissolved in 5 ml ofTHF ws added dropwise into a solution of 5 mmol (1.1 g) of the hydroxycompound obtained in 3.(1) and 2 ml of triethylamine dissolved in 20 mlof THF, and the mixture was stirred for 10 hours. After concentration ofthe reaction solution, water was added to the concentrate, and themixture was extracted with ether. After concentration of the extractedsolution, the concentrate was purified by column chromatography toobtain 2.2 g of the objective alkene compound. (Yield: 78%)

3.(3) Epoxidation

After a stream of gaseous argon was passed through a solution of 2 mmol(1.13 g) of the alkene compound obtained in 3.(2) and 3 mmol (0.52 g) ofm-chloroperbenzoic acid dissolved in 10 ml of methylene chloride todisplace the air in the solution and the reaction apparatus, thesolution was stirred for 10 hours. The reaction solution was washed withan aqueous potassium carbonate solution, dried, and concentrated, toobtain 1.11 g of a monomer (L configuration) represented by thefollowing formula. (Yield: 96%) ##STR60##

3.(4) Synthesis of polymer

After a stream of gaseous argon was passed through a solution of 1.6mmol (0.77 g) of the monomer synthesized in 1.(6) in Example 1 and 1.0mmol (0.23 g) of the monomer obtained in 3.(3) dissolved in 10 ml ofmethylene chloride to displace the air in the solution and the reactionapparatus, 0.04 mmol of stannic chloride was added to the solution, andthe mixture was allowed to stand for 5 days at room temperature. Afterconcentration of the reaction solution, the concentrate was purified bycolumn chromatography to obtain 0.81 g of a polymer (conversion rate:81%, Mn=2,800, copolymerization ratio m:n according to NMRspectrum=75:25).

EXAMPLE 4 ##STR61## 4.(1) Synthesis of p-(7-octenyloxy)benzoic acid

9.4 g of 8-bromo-1-octene, 9.0 g of ethyl p-hydroxybenzoate, and 7.6 gof potassium carbonate were refluxed in ethanol for 10 hours. Theretoadded was an aqueous solution containing 2.4 g of sodium hydroxide, andthen reflux was further continued for 10 hours. After conclusion of thereaction, the reaction solution was diluted with water, and the pH ofthe solution was lowered to 2 by dropping hydrochloric acid. Thegenerated precipitate was collected, washed sufficiently with water, anddried, to obtain 10.8 g of the objective ether compound. (Yield: 89%)

4.(2) Synthesis of 2-methylbutyl4-[p-(7-octenyloxy)benzoyloxy]biphenyl-4-carboxylate

9 g of p-(7-octenyloxy)benzoic acid obtained in 4.(1) was suspended intoluene, and the suspension was cooled in an ice bath. Thereto addeddropwise was 6 g of thionyl chloride. After conclusion of dropping, thetemperature was raised, and reaction was carried out for 6 hours at 80°C. After conclusion of the reaction, the reaction solution wasconcentrated under reduced pressure to obtain an acid chloride compound.Toluene was added to the acid chloride compound to form a toluenesolution, and the toluene solution was cooled in an ice bath.

A toluene solution containing 10 g of 2-methylbutyl4'-hydroxybiphenyl-4-carboxylate and 3 g of pyridine was added dropwiseto the above-described toluene solution of the acid chloride compound.After conclusion of dropping, the temperature was raised, and reactionwas carried out for 8 hours at 50° C. After conclusion of the reaction,the product was washed with water and dried over magnesium sulfate, andthe dried product was concentrated under reduced pressure. The residuewas recrystallized from ethanol to obtain 8.2 g of the objective estercompound. (Yield: 45%)

4.(3) Epoxidation

7.2 g of the ester compound obtained in 4.(2) was oxidized with 3 g ofm-chloroperbenzoic acid, to obtain 6.3 g of a monomer (R configuration)represented by the following formula. (Yield: 85%) ##STR62##

4.(4) Synthesis of polymer

After a stream of gaseous argon was passed through a solution of 1.6mmol (0.72 g) of the monomer synthesized in 1.(3) in Example 1 and 0.4mmol (0.21 g) of the monomer synthesized in 4.(3) dissolved in 10 ml ofmethylene chloride to displace the air in the solution and reactionapparatus, 0.20 mmol of stannic chloride was added to the solution, andthe mixture was allowed to stand for 5 days at room temperature. Afterconcentration of the reaction solution, the concentrate was purified bycolumn chromatography, to obtain 0.55 g of a polymer (conversion rate:59%, Mn=2,400, copolymerization ratio m:n according to NMRspectrum=25:75)

EXAMPLE 5 ##STR63## 5.(1) Synthesis of 1-trifluoromethylheptyl4-hydroxy-2-fluorobenzoate

The procedure as in 2.(1) in Example 2 was repeated with the exceptionthat 20 mmol of 4-acetoxy-2-fluorobenzoic acid and 15 mmol ofR-(+)-1,1,1-trifluoro-2-octanol were used as the raw materials, toobtain the objective hydroxy compound.

5.(2) Synthesis of 1-trifluoromethylheptyl4-[4'-(9-decenyloxy)benzoyloxy]-2-fluorobenzoate

The procedure as in 3.(2) in Example 3 was repeated with the exceptionthat 5 mmol of the carboxylic acid synthesized in 1.(2) in Example 1 and3 mmol of the hydroxy compound obtained in 5.(1) were used as the rawmaterials, to synthesize the objective alkene compound. (Yield: 69%)

5.(3) Epoxidation

The procedure as in 2.(3) in Example 2 was repeated with the exceptionthat 2.0 mmol (1.16 g) of the alkene compound obtained in 5.(2) was usedas the raw material, to synthesize a monomer (R configuration)represented by the following formula. (Yield: 86%) ##STR64##

5.(4) Synthesis of polymer

The procedure as in 1.(4) in Example 1 was repeated with the exceptionthat 1.0 mmol (600 mg) of the monomer obtained in 5.(3) and 1.0 mmol(450 mg) of the monomer obtained in 1.(3) in Example 1 were used as theraw materials, to synthesize a polymer (conversion rate: 68%, Mn=2,500,copolymerization ratio m:n according to NMR spectrum=48:52).

EXAMPLE 6 ##STR65## 6.(1) Synthesis of 4-(2-methylbutanoyloxy)phenol

Into a solution of 50 mmol (5.1 g) of S-(+)-2-metylbutanoic acid and 100mmol (11.0 g) of hydroquinone dissolved in 150 ml of toluene added was 1ml of concentrated sulfuric acid, and the mixture was refluxed for 3hours with stirring. After concentration of the reaction solution, theconcentrate was purified by column chromatography to obtain 7.1 g of theobjective hydroxy compound. (Yield: 73%)

6.(2) Synthesis of 4-(2-methylbutanoyloxy)phenyl4-(13-tetradecenyloxy)benzoate

The procedure as in 3.(2) in Example 3 was repeated with the exceptionthat 15 mmol (5.0 g) of 4-(13-tetradecenyloxy)benzoic acid and 10 mmol(1.9 g) of the hydroxy compound obtained in 6.(1) were used as the rawmaterials, to obtain the objective alkene compound (Yield: 80%)

6.(3) Epoxidation

The procedure as in 1.(3) in Example 1 was repeated with the exceptionthat 2.0 mmol (1.0 g) of the alkene compound obtained in 6.(2) was usedas the raw material, to synthesize a monomer (L configuration)represented by the following formula. (Yield: 93%) ##STR66##

6.(4) Synthesis of polymer

The procedure as in 1.(4) in Example 1 was repeated with the exceptionthat 1.0 mmol (510 mg) of the monomer obtained in 6.(3) and 1.0 mmol(480 mg) of the monomer synthesized in 1.(6) in Example 1 were used asthe raw materials, to synthesize a polymer (conversion rate: 82%,Mn=2,500, copolymerization ratio m:n according to NMR spectrum=55:45).

COMPARATIVE EXAMPLE 1 ##STR67## (1) Synthesis of polymer

The polymer having the repeating unit represented by the above formulawas synthesized by using the monomer synthesized in 1.(6) in Example 1,in the same manner as in Example 1. (conversion rate: 83%, Mn=2,100)

COMPARATIVE EXAMPLE 2 ##STR68## (1) Synthesis of polymer

The polymer having the repeating unit represented by the above formulawas synthesized by using the monomer synthesized in 1.(3) in Example 1,in the same manner as in Example 1. (conversion rate: 77%, Mn=2,500)

EXAMPLE 7 ##STR69## 7.(1) Synthesis of 1-methylbutyl p-hydroxybenzoate

To 9.0 g of p-acetoxybenzoic acid added dropwise was 12 g of thionylchloride. The mixture was heated to 80° C., and was then allowed toreact for 3 hours. After conclusion of the reaction, the excessivethionyl chloride was distilled out from the reaction solution underreduced pressure, to obtain an acid chloride compound. The acid chloridecompound was dissolved in toluene, and the obtained toluene solution wascooled in an ice bath. Into the toluene solution added dropwise dropwisewas a toluene solution containing 3.5 g of S-(+)-2-pentanol and 0.5 g ofpyridine. The resulting mixture was stirred overnight at roomtemperature. After conclusion of the reaction, the reaction solution waswashed with water, dried, and concentrated under reduced pressure. Theresidue was dissolved in ether. Into the ether solution added dropwisewas 10 g of benzylamine. The mixture was stirred for 5 hours at roomtemperature. After conclusion of the reaction, the product was washedwith water, dried, and concentrated under reduced pressure. The residuewas purified by column chromatography, to obtain 5.9 g of the objectiveester compound. (Yield: 71%)

7.(2) Synthesis of 1-methylbutyl 4-[4'-(9-decenyloxy)benzoyloxy]benzoate

To 5.5 g of 4-(9-decenyloxy)benzoic acid obtained in the same manner asin 1.(2) in Example 1 added was toluene, and the mixture was cooled inan ice bath. 7.4 g of thionyl chloride was added dropwise to themixture. Subsequently, reaction was carried out for 3 hours at 80° C.After conclusion of the reaction, the product was concentrated to obtainan acid chloride compound. While, 3.1 g of 1-methylbutyl4-hydroxybenzoate obtained in 7.(1) and 0.9 g of pyridine were dissolvedin toluene, and the toluene solution was cooled in an ice bath. Addeddropwise thereto was a toluene solution of the above-described acidchloride compound. Subsequently, reaction was carried out for 6 hours atroom temperature. After conclusion of the reaction, the product waswashed with water and dried over magnesium sulfate, and the solvent wasthen distilled out from the dried product under reduced pressure. Theresidue was purified by column chromatography, to obtain 6.5 g of theobjective ester compound. (Yield: 94%)

7.(3) Epoxidation

2.5 g of the ester compound obtained in 7.(2) was subjected to the sameprocedure as that in 1.(3) in Example 1, to obtain 2.2 g of a monomer (Lconfiguration) represented by the following formula. (Yield: 85%)##STR70##

7.(4) Synthesis of polymer

After a stream of gaseous argon was passed through a solution of 0.8mmol (0.39 g) of the monomer synthesized in 1.(6) in Example 1 and 1.2mmol (0.60 g) of the monomer synthesized in 7.(3) dissolved in 10 ml ofmethylene chloride to displace the air in the solution and reactionapparatus, 0.20 mmol of stannic chloride was added to the solution, andthe mixture was allowed to stand for 5 days at room temperature. Afterconcentration of the reaction solution, the concentrate was purified bycolumn chromatography, to obtain 0.73 g of a polymer (conversion rate:74%, Mn=2,800, copolymerization ratio m:n according to NMRspectrum=38:62).

EXAMPLE 8 ##STR71## 8.(1) Synthesis of 3-methylpentyl p-hydroxybenzoate

13.7 g of p-hydroxybenzoic acid and 11.4 g of(S)-(+)-3-methyl-1-pentanol were refluxed for 10 hours in toluene in thepresence of sulfuric acid, while removing out the generated water fromthe reaction system. Subsequently, the reaction solution was washed withwater to remove the sulfuric acid out. The reaction solution was thendried, concentrated, and purified by column chromatography, to obtain17.8 g of the objective ester compound (liquid state at room temperature([α]_(D) ²³ =+7.8° (CHCl₃)). (Yield: 80%)

8.(2) Synthesis of 3-methylpentyl4-[4'-(9-decenyloxy)benzoyloxy]benzoate

To 5.5 g of 4-(9-decenyloxy)benzoic acid prepared in the same manner asin 1. (2) in Example 1 added was toluene, and the mixture was cooled inan ice bath. During cooling of the mixture in an ice bath, 7.0 g ofthionyl chloride was added to the mixture. After conclusion of dropping,reaction was carried out for 7 hours at 80° C. After conclusion of thereaction, the reaction solution was concentrated to obtain an acidchloride compound. While, 4.5 g of 3-methylpentyl 4-hydroxybenzoateobtained in 8.(1) and 1.8 g of pyridine were dissolved in toluene, andthe resulting toluene solution was cooled in an ice bath. Added dropwisethereto was a toluene solution of the above-described acid chloridecompound. After conclusion of dropping, reaction was carried out for 5hours at 50° C. After conclusion of the reaction, the product was washedwith water and dried over magnesium sulfate, to obtain 7.9 g of theobjective alkene compound ([α]_(D) ²³ =+4.4° (CHCl₃)). (Yield: 86%)

8.(3) Epoxidation

4.8 g of the alkene compound obtained in 8.(2) was subjected to the sameprocedure as in 1.(3) in Example 1, to obtain 4.9 g of a monomer (Lconfiguration) represented by the following formula. (Yield: 99%)##STR72##

8.(4) Synthesis of polymer

After a stream of gaseous argon was passed through a solution of 0.8mmol (0.39 g) of the monomer synthesized in 1.(6) in Example 1 and 1.2mmol (0.60 g) of the monomer synthesized in 8.(3) dissolved in 10 ml ofmethylene chloride to displace the air in the solution and reactionapparatus, 0.20 mmol of stannic chloride was added to the solution, andthe mixture was then allowed to stand for 5 days at room temperature.After concentration of the reaction solution, the concentrate waspurified by column chromatography, to obtain 0.70 g of a polymer(conversion rate: 71%, Mn=3,000, copolymerization ratio m:n according toNMR spectrum=43:57)

The helical pitches, phase transition behaviors, and response speeds toelectric field of the polymers obtained in the above-described Examples1 to 8 and Comparative examples 1 and 2 were shown in Table 1.

EXAMPLE 9 ##STR73## 9.(1) Synthesis of 2-methylbutyl 4-hydroxybenzoate

4.0 g of p-hydroxybenzoic acid and 12.5 g of (-)-2-methylbutanol wererefluxed for 6 hours in toluene in the presence of sulfuric acid, whileremoving the generated water out from the reaction system. Subsequently,the reaction solution was washed with water to remove sulfuric acid out.The reaction solution was then dried and concentrated, and theconcentrate was purified by column chromatography, to obtain 5.0 g ofthe objective ester compound (liquid state at room temperature, [α]_(D)²³ =4.9° (CHCl₃)). (Yield: 83%)

9.(2) Synthesis of 2-methylbutyl 4-[4'-(9-decenyloxy)benzoyloxy]benzoate

10.0 g of 10-chloro-1-decene and 25 g of sodium iodide were allowed toreact in 2-butanone for 10 hours at 80° C. to replace chloro group withiodo group. After the reaction solution was washed with water and dried,the solvent was removed out from the dried solution. 11.5 g of ethylp-hydroxybenzoate and 9.6 g of potassium carbonate were then added tothe residue, and the mixture was then refluxed in absolute ethanol for15 hours. After addition of an aqueous potassium hydroxide solutioncontaining 4.0 g of potassium hydroxide, the mixture was further heatedat 80° C. for 5 hours. After conclusion of the reaction, the reactionsolution was acidified with hydrochloric acid and then concentratedunder reduced pressure. Water was added to the residue to obtain asuspension, and insoluble matter in the suspension was collected fromthe suspension and dried, to obtain 9.5 g of 4-(9-decenyloxy)benzoicacid. (Yield: 60%) To 4.5 g of the obtained 4 -(9-decenyloxy)benzoicacid added was toluene, and the resulting toluene solution was cooled inan ice bath. During cooling of the toluene solution in the ice bath, 3.5g of thionyl chloride was added dropwise thereto. After conclusion ofdropping, reaction was carried out for 7 hours at 80° C. Afterconclusion of the reaction, the reaction solution was concentrated toobtain an acid chloride compound. While, 4.5 g of 2-methylbutyl4-hydroxybenzoate obtained in 9.(1) and 1.8 g of pyridine were dissolvedin toluene, and the resulting toluene solution was cooled in an icebath. Added dropwise thereto was a toluene solution of theabove-described acid chloride compound. After conclusion of dropping thetoluene solution, the reaction was carried out for 5 hours at 50° C.

After conclusion of the reaction, the product was washed with water anddried over magnesium sulfate, and the dried matter was purified bycolumn chromatography, to obtain 5.5 g of the objective alkene compound.(Yield: 72%)

9.(3) Epoxidation

After a stream of gaseous argon was passed through a solution of 5.5 gof the alkene compound obtained in 9.(2) and 3 mmol (0.52 g) ofm-chloroperbenzoic acid dissolved in 10 ml of methylene chloride todisplace the air in the solution and reaction apparatus, the solutionwas stirred for 10 hours. The reaction solution was then washed with anaqueous solution of potassium carbonate, dried, and concentrated, toobtain 5.2 g of a monomer represented by the following formula. (Yield:92%) ##STR74##

9.(4) Synthesis of polymer

After a stream of gaseous argon was passed through a solution of 2.0mmol (0.96 g) of the monomer synthesized in 9.(3) dissolved in 10 ml ofmethylene chloride to displace the air in the solution and reactionapparatus, 0.5 mmol (22 mg) of ethylene oxide and 0.25 mmol of stannicchloride were added to the solution, and the mixture was then allowed tostand for 5 days at room temperature. After concentration of thereaction solution, the concentrate was purified by columnchromatography, to obtain 0.70 g of a polymer (conversion rate: 71%,Mn=2,200, copolymerization ratio m:n according to NMR spectrum=77:23).

EXAMPLE 10 ##STR75## 10.(1) Synthesis of polymer

After a stream of gaseous argon was passed through a solution of 2.0mmol (0.96 g) of the monomer synthesized in 9.(3) in Example 9 dissolvedin 10 ml of methylene chloride to displace the air in the solution andreaction apparatus, 2.0 mmol (0.09 g) of ethylene oxide and 0.40 mmol ofstannic chloride were added to the solution, and the mixture was allowedto stand for 5 days at room temperature. After concentration of thereaction solution, the concentrate was purified by columnchromatography, to obtain 0.64 g of a polymer (conversion rate: 64%,Mn=1,700, copolymerization ration m:n according to NMR spectrum=54:46).

EXAMPLE 11 ##STR76## 11.(1) Synthesis of polymer

After a stream of gaseous argon was passed through a solution of 2.0mmol (0.96 g) of the monomer synthesized in 9.(3) in Example 9 dissolvedin 10 ml of methylene chloride to displace the air in the solution andreaction apparatus, 2.0 mmol (0.12 g) of propylene oxide and 0.40 mmolof stannic chloride were added to the solution, and the mixture wasallowed to stand for 5 days at room temperature. After concentration ofthe reaction solution, the concentrate was purified by columnchromatography, to obtain 0.71 g of a polymer (conversion rate: 72%,Mn=1,600, copolymerization ratio m:n according to NMR spectrum=60:40).

EXAMPLE 12 ##STR77## 12.(1) Synthesis of 4-(2-methylbutoxy)phenol

Into a n-butanol suspension containing 37 mmol (9.0 g) of 2-methylbutylp-toluenesulfonate prepared by tosylating S-(-)-2-methylbutanol and 74mmol (8.2 g) of hydroquinone, added dropwise was a solution of 50 mmol(2.1 g) of sodium hydroxide dissolved in a solvent mixture of 3 ml ofwater and 10 ml of n-butanol. After conclusion of the dropping, themixture was then stirred for 8 hours at 120° C. After addition of water,the reaction solution was extracted with ether, and the extractedsolution was dried and concentrated. The concentrate was purified bycolumn chromatography, to obtain 4.8 g of the objective ether compound.(Yield: 72%)

12.(2) Synthesis of 4-(2-methylbutoxy)phenyl 4-(9-decenyloxy)benzoate

10.0 g of 10-chloro-1-decene and 25 g of sodium iodide were allowed toreact in 2-butanone for 10 hours at 80° C., to replace the chloro groupwith iodo group. After the resulting product was washed with water anddried, the solvent was removed out from the dried product. To theresulting residue added were 11.5 g of ethyl p-hydroxybenzoate and 9.6 gof potassium carbonate, and the mixture was then refluxed for 15 hoursin an absolute ethanol. After addition of an aqueous potassium hydroxidesolution containing 4.0 g of potassium hydroxide, the mixture wasfurther heated for 5 hours at 80° C. After conclusion of the reaction,the reaction solution was acidified with hydrochloric acid and was thenconcentrated under reduced pressure. Water was added to the residue toobtain a suspention, and the insoluble matter in the suspension wascollected from the suspension and was dried to obtain 9.5 g of4-(9-decenyloxy)benzoic acid. (Yield: 60%)

Subsequently, a toluene solution containing 10 mmol (2.8 g) of4-(9-decenyloxy)benzoic acid and 30 mmol (3.6 g) of thionyl chloridedissolved was allowed to react for 3 hours at 100° C. and was thenconcentrated under reduced pressure, to obtain an acid chloridecompound. After a solution of the acid chloride compound dissolved in 5ml of THF was added dropwise into a solution of 8 mmol (1.4 g) of theether compound obtained in 12.(1) and 2 ml of triethylamine dissolved in20 ml of THF, the resulting mixture was stirred for 10 hours. Afteraddition of water, the reaction solution was extracted with ether, andthe extracted solution was dried and concentrated. The concentrate waspurified by column chromatography to obtain 2.2 g of the objectivealkene compound. (Yield: 63%)

12.(3) Epoxidation

After a stream of gaseous argon was passed through a solution of 2 mmol(0.84 g) of the alkene compound obtained in 12.(2) and 3 mmol (0.52 g)of m-chloroperbenzoic acid dissolved in 10 ml of methylene chloride todisplace the air in the solution and the reaction apparatus, thesolution was stirred for 10 hours. After the reaction solution waswashed with an aqueous potassium carbonate solution, the washed reactionsolution was dried and concentrated, to obtain 0.82 g of a monomerrepresented by the following formula. (Yield: 90%) ##STR78##

12.(4) Synthesis of polymer

After a stream of gaseous argon was passed through a solution of 2.0mmol (0.91 g) of the monomer synthesized in 12.(3) dissolved in 10 ml ofmethylene chloride to displace the air in the solution and the reactionapparatus, 0.5 mmol (22 mg) of etylene oxide and 0.25 mmol of stannicchloride were added to the solution, and the mixture was then allowed tostand for 5 days at room temperature. After concentration of thereaction solution, the concentrate was purified by columnchromatography, to obtain 0.59 g of a polymer (conversion rate: 63%,Mn=2,600, copolymerization ratio m:n according to NMR spectrum=88:12).

EXAMPLE 13 ##STR79## 13.(1) Synthesis of 2-fluorooctyl p-hydroxybenzoate

To 5.4 g of p-acetoxybenzoic acid added dropwise was 11 g of thionylchloride. The resulting mixture was heated to 80° C. and then allowed toreact for 3 hours. After conclusion of the reaction, the excessivethionyl chloride was distilled out from the reaction solution underreduced pressure, to obtain an acid chloride compound. The acid chloridecompound was dissolved in toluene and the resulting solution was cooledin an ice bath. Added dropwise thereto was a toluene solution containing4.4 g of (-)-2-fluorooctanol and 3 g of pyridine. The obtained mixturewas stirred overnight at room temperature. After conclusion of thereaction, the reaction solution was washed with water, dried, andconcentrated under reduced pressure. The residue was dissolved in ether.10 g of benzylamine was added dropwise to the ether solution. Theresulting mixture was stirred for 5 hours at room temperature. Afterconclusion of the reaction, the product was washed with water, dried,and concentrated under reduced pressure. The residue was purified bycolumn chromatography, to obtain 4.9 g of the objective ester compound.(Yield: 73%)

13.(2) Synthesis of 2-fluorooctyl4-[4'-(9-decenyloxy)benzoyloxy]benzoate

To 3.0 g of 4-(9-decenyloxy)benzoic acid prepared in the same manner asin 9.(2) in Example 9 added was toluene, and the mixture was cooled inan ice bath. 2.0 g of thionyl chloride was added dropwise to themixture. Subsequently, reaction was carried out for 3 hours at 80° C.After conclusion of the reaction, the product was concentrated to obtainan acid chloride compound. While, 1.7 g of 2-fluorooctyl4-hydroxybenzoate and 0.9 g of pyridine were dissolved in toluene, andthe resulting solution was cooled in an ice bath. Added dropwise theretowas a toluene solution of the above-described acid chloride compound.Reaction was then carried out for 15 hours at room temperature. Afterconclusion of the reaction, the product was washed with water and driedover magnesium sulfate, and the solvent was then distilled out from thedried product under reduced pressure. The residue was purified by columnchromatography to obtain 2.8 g of the objective ester compound. (Yield:85%)

13.(3) Epoxidation

2.8 g of the ester compound obtained in 13.(2) was subjected to the sameprocedure as in 9.(3) in Example 9, to obtain 2.6 g of a monomerrepresented by the following formula. (Yield: 91%) ##STR80##

13.(4) Synthesis of polymer

After a stream of gaseous argon was passed through a solution of 2.0mmol (1.08 g) of the monomer synthesized in 13.(3) dissolved in 10 ml ofmethylene chloride to displace the air in the solution and the reactionapparatus, 0.5 mmol (50 mg) of 1,2-epoxyhexane and 0.25 mmol of stannicchloride were added to the solution, and the mixture was then allowed tostand for 5 days at room temperature. After concentration of thereaction solution, the concentrate was purified by columnchromatography, to obtain 0.88 g of a polymer (conversion rate: 78%,Mn=2,400, copolymerization ratio m:n according to NMR spectrum=82:18).

EXAMPLE 14 ##STR81## 14.(1) Synthesis of 2-chloro-3-methylpentyl4'-(9-decenyloxy)biphenyl-4-carboxylate

To 4.0 g of 4'-(9-decenyloxy)biphenyl-4-carboxylic acid was addedtoluene, and the mixture was cooled in an ice bath. Added dropwisethereto was 2.0 g of thionyl chloride. Reaction was then carried out for7 hours at 80° C. After conclusion of the reaction, the reactionsolution was concentrated to obtain an acid chloride compound. 1.7 g of2-chloro-3-methylpentanol and 1.0 g of pyridine were dissolved intoluene, and the solution was cooled in an ice bath. Added dropwisethereto was a toluene solution of the above-described acid chloridecompound. Reaction was then carried out for 15 hours at roomtemperature. After conclusion of the reaction, the reaction solution waswashed with water and dried over magnesium sulfate, and the solvent wasdistilled out from the dried reaction solution under reduced pressure.The residue was purified by column chromatography to obtain 4.3 g of theobjective ester compound. (Yield: 80%)

14.(2) Epoxidation

4.3 g of the ester compound obtained in 14.(1) was subjected to the sameprocedure as in 9.(3) in Example 9, to obtain 4.2 g of a monomerrepresented by the following formula. (Yield: 95%) ##STR82##

14.(3) Synthesis of polymer

After a stream of gaseous argon was passed through a solution of 2.0mmol (0.97 g) of the monomer synthesized in 14.(2) to displace the airin the solution and the reaction apparatus, 0.5 mmol (22 mg) of ethyleneoxide and 0.25 mmol of stannic chloride were added to the solution, andthe resulting mixture was allowed to stand for 5 days at roomtemperature. After the reaction solution was concentrated, theconcentrate was purified by column chromatography, to obtain 0.58 g of apolymer (conversion rate: 58%, Mn=2,400, copolymerization ratio m:naccording to NMR spectrum=84:16).

EXAMPLE 15 ##STR83## 15.(1) Synthesis of p-(7-octenyloxy)benzoic acid

9.4 g of 8-bromo-1-octene, 9.0 g of ethyl p-hydroxybenzoate, and 7.6 gof potassium carbonate were refluxed in ethanol for 10 hours. Addedthereto was an aqueous solution containing 2.4 g of sodium hydroxide,and reflux was further continued for 10 hours. After conclusion of thereaction, the reaction solution was diluted with water, and the pH ofthe diluted solution was lowered to 2 by dropping hydrochloric acidthereto. The generated precipitate was collected, and was then washedwith water sufficiently and dried, to obtain 10.8 g of the objectiveether compound. (Yield: 89%)

15.(2) Synthesis of 2-methylbutyl4-[p-(7-octenyloxy)benzoyloxy]biphenyl-4-carboxylate

9 g of p-(7-octenyloxy)benzoic acid obtained in 15.(1) was suspended intoluene, and the suspension was cooled in an ice bath. Added dropwisethereto was 6 g of thionyl chloride. After conclusion of the dropping,the temperature was raised and reaction was carried out for 6 hours at80° C. After conclusion of the reaction, the reaction solution wasconcentrated under reduced pressure, to obtain an acid chloridecompound. Toluene was added to the acid chloride compound, and theresulting toluene solution was cooled in an ice bath. A toluene solutioncontaining 10 g of 2-methylbutyl 4'-hydroxybiphenyl-4-carboxylate and 3g of pyridine was added dropwise into the above-described toluenesolution of the acid chloride compound. After conclusion of dropping,the temperature was raised, and reaction was carried out for 8 hours at50° C. After conclusion of the reaction, the product was washed withwater, dried over magnesium sulfate, and concentrated under reducedpressure. The residue was recrystallized from ethanol, to obtain 8.2 gof the objective ester compound. (Yield: 45%)

15.(3) Epoxidation

7.2 g of the ester compound obtained in 15.(2) was acidified with 3 g ofm-chloroperbenzoic acid, to obtain 6.3 g of a monomer represented by thefollowing formula. (Yield: 85%) ##STR84##

15.(4) Synthesis of polymer

After a stream of gaseous argon was passed through an solution of 2.0mmol (1.06 g) of the monomer synthesized in 15.(3) dissolved in 10 ml ofmethylene chloride to displace the air in the solution and the reactionapparatus, 2.0 mmol (0.09 g) of ethylene oxide and 0.40 mmol of stannicchloride were added to the solution, and the mixture was then allowed tostand for 5 days at room temperature. After concentration of thereaction solution, the concentrate was purified by columnchromatography, to obtain 0.74 g of a polymer (conversion rate: 64%,Mn=2,200, copolymerization ratio m:n according to NMR spectrum=80:20).

EXAMPLE 16 ##STR85## 16.(1) Synthesis of 2-methylbutyl4[4'-(9-decenyloxy)-biphenylyl-4-carbonyloxy]benzoate

To 5.0 g of 4'-(9-decenyloxy)bipenyl-4-carboxylic acid added wastoluene, and the mixture was then cooled in an ice bath. 2.6 g ofthionyl chloride was added dropwise to the mixture. Subsequently,reaction was carried out for 7 hours at 80° C. After conclusion of thereaction, the product was concentrated to obtain an acid chloridecompound. 3.1 g of 2-methylbutyl 4-hydroxybenzoate prepared in the samemanner as in 9.(1) in Example 9 and 1.5 g of pyridine were dissolved intoluene, and the toluene solution was cooled in an ice bath. Addeddropwise thereto was a toluene solution of the above-described acidchloride compound. Subsequently, reaction was carried out for 5 hours at50° C. After conclusion of the reaction, the product was washed withwater and dried over magnesium sulfate, and the solvent was distilledout from the dried product under reduced pressure. The residue waspurified by column chromatography to obtain 5.2 g of the objective estercompound. (Yield: 68%)

16.(2) Epoxidation

5.2 g of the ester compound obtained in 16.(1) was subjected to the sameprocedure as in 9.(3) in Example 9, to obtain 4.9 g of a monomerrepresented by the following formula. (Yield: 92%) ##STR86##

16. (3) Synthesis of polymer

After a stream of gaseous argon was passed through a solution of 2.0mmol (1.12 g) of the monomer synthesized in 16.(2) dissolved in 10 ml ofmethylene chloride to displace the air in the solution and the reactionapparatus, 2.0 mmol (0.09 g) of ethylene oxide and 0.40 mmol of stannicchloride were added to the solution, and the mixture was then allowed tostand for 5 days at room temperature. After concentration of thereaction solution, the concentrate was purified by columnchromatography, to obtain 0.73 g of a polymer (conversion rate: 60%,Mn=2,100, copolymerization ratio m:n according to NMR spectrum=78:22).

EXAMPLE 17 ##STR87## 17.(1) Synthesis of 1-trifluoromethylheptyl4-hydroxy-2-fluorobenzoate

A solution of 20 mmol (4.0 g) of 4-acetoxy-2-fluorobenzoic acid and 60mmol (7.2 g) of thionyl chloride dissolved in 100 ml of toluene wasstirred for 2 hours at 80° C., and the reaction solution wasconcentrated under reduced pressure, to obtain an acid chloridecompound. A solution of the acid chloride compound dissolved in 10 ml ofTHF was added dropwise to a solution of 15 mmol (2.8 g) ofR-(+)-1,1,1-trifluoro-2-octanol and 5 ml of triethylamine dissolved in30 ml of THF, and the mixture was then stirred for 10 hours. Afterconcentration of the reaction solution, water was added to theconcentrate, and the mixture was then extracted with ether. Afterconcentration of the extracted solution, the concentrate was dissolvedin 200 ml of ether. To the resulting ether solution added was 20 ml ofbenzylamine, and the mixture was stirred for 5 hours. The reactionsolution was washed with water and was then purified by columnchromatography, to obtain 2.5 g of the objective hydroxy compound.(Yield: 52%)

17. (2) Synthesis of 1-trifluoromethylheptyl4-[4'-(9-decenyloxy)benzoyloxy]-2-fluorobenzoate

To 2.8 g of p-(9-decenyloxy)benzoic acid prepared in the same manner asin 9.(2) in Example 9 added was toluene, and the resulting mixture wascooled in an ice bath. 5.0 g of thionyl chloride was then added dropwiseto the toluene solution. Reaction was then carried out for 7 hours at80° C. After conclusion of the reaction, the reaction solution wasconcentrated under reduced pressure, to obtain crude p-decenyloxybenzoylchloride. 1.6 g of the hydroxy compound obtained in 17.(1) and 3.3 g ofpyridine were dissolved in toluene, and the resulting toluene solutionwas cooled in an ice bath. A toluene solution containing the above crudep-decenyloxybenzoyl chloride was added dropwise into the toluenesolution. Subsequently, reaction was carried out for 5 hours at 50° C.After conclusion of the reaction, the reaction solution was washed withwater and dried over magnesium sulfate, and the solvent was distilledout under reduced pressure. The residue was purified by columnchromatography, to obtain 2.0 g of the objective alkene compound.(Yield: 69%)

17.(3) Epoxidation

A monomer represented by the following formula was synthesized in thesame manner as in 9.(3) in Example 9 using 2.0 mmol (1.16 g) of thealkene compound obtained in 17.(2) as the raw material. (Yield: 86%)##STR88##

17.(4) Synthesis of polymer

The same procedure as in 11.(1) in Example 11 was repeated with theexception that 1.0 mmol (600 mg) of the monomer obtained in 17.(3) and0.5 mmol (29 mg) of propylene oxide were used as the raw materials, tosynthesize a polymer (conversion rate: 78%, Mn=2,000, copolymerizationratio m:n according to NMR spectrum=70:30).

EXAMPLE 18 ##STR89## 18.(1) Synthesis of 4-(2-methylbutanoyloxy)phenol

Into a solution of 50 mmol (5.1 g) of S-(+)-2-methylbutanoic acid and100 mmol (11.0 g) of hydroquinone dissolved in 150 ml of toluene addedwas 1 ml of concentrated sulfuric acid, and the mixture was thenrefluxed for 3 hours with stirring. After concentration of the reactionsolution, the concentrate was purified by column chromatography, toobtain 7.1 g of the objective hydroxy compound. (Yield: 73%)

18.(2) Synthesis of 4'-(2-methylbutanoyloxy)phenyl4-(13-tetradecenyloxy)benzoate

The procedure as in 12.(2) in Example 12 was repeated with the exceptionthat 15 mmol (5.0 g) of 4-(13-tetradecenyloxy)benzoic acid and 10 mmol(1.9 g) of the hydroxy compound obtained in 18.(1) were used as the rawmaterials, to synthesize the objective alkene compound. (Yield: 80%)

18.(3) Epoxidation

The procedure as in 12.(3) in Example 12 was repeated with the exceptionthat 2.0 mmol (1.0 g) of the alkene compound obtained in 18.(2) was usedas the raw material. (Yield: 93%)

18.(4) Synthesis of polymerization

The procedure as in 11.(1) in Example 11 was repeated with the exceptionthat 1.0 mmol (510 mg) of the monomer obtained in 18.(3) and 0.5 mmol(29 mg) of propylene oxide were used as the raw materials, to synthesizea polymer (conversion rate: 78%, Mn=2,200, copolymerization ratio m:naccording to NMR spectrum=72:28).

COMPARATIVE EXAMPLE 3 ##STR90## (1) Synthesis of polymer

The polymer having the repeating unit represented by the above formulawas synthesized by using the monomer synthesized in 13.(3) in Example13, in the same manner as in Example 9. (conversion rate: 63%, Mn=2,700)

COMPARATIVE EXAMPLE 4 ##STR91## (1) Synthesis of polymer

The polymer having the repeating unit represented by the above formulawas synthesized by using the monomer synthesized in 14.(2) in Example14, in the same manner as in Example 9. (conversion rate: 75%, Mn=2,900)

COMPARATIVE EXAMPLE 5 ##STR92## (1) Synthesis of polymer

The polymer having the repeating unit represented by the above formulawas synthesized by using the monomer synthesized in 17.(3) in Example17, in the same manner as in Example 9. (conversion rate: 83%, Mn=2,100)

The phase transition behaviors, helical pitches, and response speeds toelectric field of the polymers obtained in Examples 9 to 18 andComparative Examples 3 to 5 are shown in Table 2.

    TABLE 1       Copoly-  Helical Response time (ms)  merization Phase transition     behavior Pitch Measuring tem- Repeating Unit ratio (°C.) (μm)     perature (°C.))                Example 1      ##STR93##      m:n =      58:42     ##STR94##      4.2 25(45)  30 (30) 70(15)      ##STR95##      Example 2     ##STR96##      m:n =      60:40     ##STR97##      3.8  3(40)  5 (30)  20(20) 100 (10)      ##STR98##      Example 3     ##STR99##      m:n =      75:25     ##STR100##      2.5 10(60) 100 (10)      ##STR101##      Example 4     ##STR102##      m:n =      25:75     ##STR103##      2.8 48(65)      ##STR104##      Example 5     ##STR105##      m:n =      48:52     ##STR106##      4.8  9(30)      ##STR107##      Example 6     ##STR108##      m:n =      55:45     ##STR109##      3.4 24(45)      ##STR110##      Example 7     ##STR111##      m:n =      38:62     ##STR112##      3.5  2(20)  20 (10)      ##STR113##      Example 8     ##STR114##      m:n =      43:57     ##STR115##      4.5 15(30) 300 (10)      ##STR116##      Compar-ativeExample 1     ##STR117##      ##STR118##      2.0 10(30)      Compar-ativeExample 2     ##STR119##      ##STR120##      1.8 90(30)

    TABLE 2       Copoly-  Helical Response time (ms)  merization Phase transition     behavior pitch (Measuring tem- Repeating unit ratio (°C.) (μm)     perature (°C.))             Example 9      ##STR121##      m:n =      77:23     ##STR122##      4.2  2 (20)   (CH.sub.2 CH.sub.2 O).sub.n      Example 10     ##STR123##      m:n =      54:46     ##STR124##      2.4  4(-10)   (CH.sub.2 CH.sub.2 O).sub.n      Example 11     ##STR125##      m:n =      60:40     ##STR126##      3.4  2 (25)      ##STR127##      Example 12     ##STR128##      m:n =      88:12     ##STR129##      2.2  4 (20)   (CH.sub.2 CH.sub.2 O).sub.n       Example 13     ##STR130##      m:n =      82:18     ##STR131##      1.8  1 (25)      ##STR132##      Example 14      ##STR133##      m:n =      84:16     ##STR134##      1.8  1 (45)   (CH.sub.2 CH.sub.2 O).sub.n      Example 15     ##STR135##      m:n =      80:20     ##STR136##      2.4  12 (60)   (CH.sub.2 CH.sub.2 O).sub.n      Example 16     ##STR137##      m:n =      78:22     ##STR138##      2.5  10 (50)   (CH.sub.2 CH.sub.2 O).sub.n      Example 17     ##STR139##      m:n =      70:30     ##STR140##      2.0  2 (10)      ##STR141##      Example 18      ##STR142##      m:n =      72:28     ##STR143##      3.2  3 (35)      ##STR144##      Compar-ativeExample 3      ##STR145##      ##STR146##      1.1  2 (35)      Compar-ativeExample 4     ##STR147##      ##STR148##      1.0  2 (40)      Compar-ativeExample 5     ##STR149##      ##STR150##      1.5  15 (30)

What is claimed is: PG,99
 1. A liquid-crystalline copolymer comprisingthe copolymerization product of;(a) at least one liquid-crystallineepoxy compound which has a helical structure and is represented by thefollowing general formula (1) and (c) at least onenon-liquid-crystalline epoxy compound represented by the followinggeneral formula (5),the copolymerization product comprising at least onerepeating unit represented by the following general formula (3) and atleast one repeating unit represented by the following general formula(6), wherein the molar ratio of the repeating unit (3) to the repeatingunit (6) is from 99:1 to 10:90; ##STR151## wherein R¹ is a grouprepresented by --(CH₂)_(k) --OR³, wherein k is an integer having a valueof from 1 to 30, R³ is a group represented by --A_(p) --X--B_(q) --R⁴,wherein X is a single bond, --COO-- or --OCO--, p and q eachindependently are an integer having a value of 1 or
 2. A is ##STR152## aand b each independently being an integer having a value of from 0 to 4and being identical with or different from each other, each Y being ahalogen atom and being identical with or different from the others, Aand B are identical with or different from each other, and R⁴ is--COOR⁵, --OCOR⁵ or --OR⁵,wherein R⁵ is ##STR153## R⁶ and R⁷ eachindependently being --CH₃, a halogen atom, --CN or --CF₃, r and t eachindependently being an integer having a value of from 0 to 10, with theproviso that t is not 0 when R⁷ is --CH₃, s being an integer of 0 or 1,and C marked with * being an asymmetric carbon atom; and R⁸ is --H or agroup represented by --(CH₂)_(u) CH₃, u being an integer having a valueof from 0 to
 9. 2. The liquid-crystalline copolymer as claimed in claim1, wherein k is an integer having a value of from 4 to
 16. 3. Theliquid-crystalline copolymer as claimed in claim 2, wherein R³ is##STR154##
 4. The liquid-crystalline copolymer as claimed in claim 3,wherein R⁵ is ##STR155##
 5. The liquid-crystalline copolymer as claimedin claim 1, wherein R¹ is ##STR156##